[FFmpeg-devel] [PATCH v2 2/4] avcodec/cbs: Only write extradata if there is something to write

From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
To: ffmpeg-devel@ffmpeg.org
Cc: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Subject: [FFmpeg-devel] [PATCH v2 2/4] avcodec/cbs: Only write extradata if there is something to write
Date: Tue, 20 Sep 2022 18:46:43 +0200
Message-ID: <GV1P250MB07377F53DE38EBEC167F708F8F4C9@GV1P250MB0737.EURP250.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <GV1P250MB0737575554F114CCDEDBD6618F4C9@GV1P250MB0737.EURP250.PROD.OUTLOOK.COM>

It is e.g. legal for an ISOBMFF avcc to contain zero parameter sets.
In this case the annex B that we produce would be empty and therefore
useless. This happens e.g. with mov/frag_overlap.mp4 from the
FATE-suite.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
Maybe check for the number of units to write instead?

 libavcodec/cbs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/libavcodec/cbs.c b/libavcodec/cbs.c
index 07ae658a4c..8d6e3c3442 100644
--- a/libavcodec/cbs.c
+++ b/libavcodec/cbs.c
@@ -438,6 +438,10 @@ int ff_cbs_write_extradata(CodedBitstreamContext *ctx,
         return err;
 
     av_freep(&par->extradata);
+    par->extradata_size = 0;
+
+    if (!frag->data_size)
+        return 0;
 
     par->extradata = av_malloc(frag->data_size +
                                AV_INPUT_BUFFER_PADDING_SIZE);
-- 
2.34.1

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